1. Field of the Invention
The present invention relates to devices for crushing materials within a wide range of hardness and, more particularly, relates to gyratory or cone crushers.
2. Description of the Prior Art
Among the main operational characteristics of crushers is the fineness or coarseness of the crushing they perform and the feasibility of adjusting them up to a required particle size of crushed product. Highly desirable is stepping up the degree of automation of crushers, e.g. providing for their continuous performance with a stable throughput and product size. Stability of these characteristics of cone crushers is predominantly dependent on the stability of the size of the discharge opening or slot between the inner and outer cones, which is prone to significant variations, e.g. due to wearing out of the armored working surfaces of the cones. To maintain a desired size of the discharge opening, cone crushers are equipped, as a rule, with means for controlling the size of this discharge opening.
The feasibility of adjusting a cone crusher to a required product size is dependent on the design of the means imparting gyratory motion to the inner cone.
There is known a cone crusher (A. S. Donchenko et al., Spravochnik mekhanika rudoobogatitelnoi fabriki, 1975, Nedra Moscow, p.50) which includes a housing, an outer hollow cone attached to the housing by a threaded joint, an inner cone received within the hollow outer cone with a discharge slot defined therebetween, mounted for rotation about its axis and gyrations about a center belonging to the axis of the outer cone, a shaft extending coaxially with the inner cone and fast therewith, and means for imparting gyrations to the inner cone, mounted on the shaft for rotation thereabout and operatively connected with a drive through a bevel gear couple. The means for adjusting the size of the discharge slot in this cone crusher is the threaded joint of the outer cone with the housing, and the adjustment of the size of the slot is carried out by vertically displacing the outer cone relatively to the inner one by rotating the former in its threaded joint. However, this operation can be performed only with the crushing space having been emptied of the material being crushed, i.e. with the crushing operation discontinued, which adversely affects the throughput of the crusher.
The means for imparting gyrations to the inner cone in this known crusher includes a driven eccentric weight providing for a specific predetermined angle of nutation of gyrations of the inner cone, dependent on the degree of eccentricity of the eccentric weight, which, in its turn, defines the degree of compression of the material in the crushing space between the cones, and, hence, defined the actual degree of disintegration or crushing which in most cases is within 1:5.
When the degree of disintegration or crushing is to be varied, i.e. when the crusher is to be adjusted for a required product size, the driven eccentric weight in the crusher being described has to be replaced with another weight of a different eccentricity; in most cases the higher degree of crushing is paid for in terms of a lower throughput.
A variation of the degree of crushing, i.e. adjustment of a crusher to a required product size within a relatively wide range is possible in a crusher where the means for imparting gyrations to the inner cone includes an unbalanced vibrator mounted on the shaft of the inner cone with the aid of a sliding-contact bearing and operatively connected with the driven gear of the bevel gear couple through a flexible shaft, e.g. a universal-joint shaft extending coaxially with the outer cone (U.S. Pat. No. 4,073,446).
The provision in the crusher of the unbalanced vibrator permits replacement of the stable operative connections between the cones, characteristic of crushers with driven eccentric weights, by dynamic connections. This, in its turn, provides for the inner cone rolling directly along the outer cone in engagement therewith when no material is present therebetween. This kind of interaction of the cones provides for disintegrating a material in a thick layer, with the degree of crushing being as high as 1:20 and with the material being bulk-fed into the crusher directly from a feed hopper.
Furthermore, the unbalanced vibrator can be designed to feature a variable static moment, which provides for easily varying the degree of the crushing of a product, e.g. within a range from 1:4 to 1:20, without affecting the throughput of the crusher. A variation of the static moment of the unbalanced vibrator would vary the centrifugal force developed by the vibrator and, consequently, the crushing effort, which would vary the degree of deformation of the material, and ultimately the product size.
However, the means for adjusting the size of the discharge slot in the cone crusher being described is similar to its counterpart in the previously described cone crusher in that it also requires an interruption of the crushing operating and emptying of the crushing space for carrying out an adjustment of the discharge slot.
Finally, there is known a cone crusher comprising a housing, an outer hollow cone fixedly mounted in this housing, an inner cone received within the hollow outer cone with a discharge slot defined therebetween, mounted for rotation about its axis and for gyrations relative to a centre belonging to the axis of the outer cone, a shaft extending coaxially with the inner cone and fast therewith, means for adjusting the size of the discharge slot including a mechanism for axial reciprocation of the shaft, having its power member operatively connected with the free end of the shaft through a self-aligning spherical joint, and means for imparting gyrations to the inner cone, mounted on the shaft for sliding therealong and rotating thereabout, connected with a drive through a bevel gear couple of which the driven gear is arranged concentrically with the line of the motion of the actuating member of the reciprocation mechanism, the central bore of the driven gear being in excess of the diameter of the shaft (KRUPP, "Kubria-Kegelbrecher").
The means for imparting gyrations to the inner cone in this known crusher includes an eccentric bushing-mounted on the shaft of the inner cone with the aid of a sliding-contact bearing and fastened by its bottom end to the driven gear of the bevel gear couple. The means for adjusting the size of the discharge slot in the crusher, unlike the previously described crushers, is in the form of a reciprocation mechanism, i.e. of a hydraulic power cylinder of which the power member is operable for reciprocating the shaft of the inner cone and, hence, the inner cone itself with respect to the outer cone fixed in the housing, which varies the size of the discharge slot of the crusher. This adjustment does not necessitate the emptying of the crushing space between the cones of the material being handled, thus enhancing the conditions for controlling the process performed by the crusher with a relatively simple design of the latter. There is also a possibility for automating the operation of adjusting the size of the discharge slot by relatively simple means. However, this last-described crusher is not free from the drawbacks mentioned hereinabove in the description of the crusher with a driven eccentric weight.
It should be pointed out that the central arrangement of the hydraulic power cylinder axially of the outer cone precludes the incorporation in the last-described crusher of an unbalanced vibrator as the means for imparting gyrations to the inner cone, including in its drive the centrally arranged flexible driving shaft.